← Back to blog

Proprietary Estoppel for SQE1

Part of our SQE1 Land Law guide → View the full SQE1 Land Law guide

15 May 2026

Proprietary estoppel is an equitable doctrine that prevents a landowner from going back on a promise about land when the promisee has relied on it to their detr

Proprietary Estoppel

Land Law > Proprietary Estoppel

Proprietary estoppel is an equitable doctrine that prevents a landowner from going back on a promise about land when the promisee has relied on it to their detriment. Candidates frequently lose marks by misunderstanding the three elements (assurance, reliance, detriment), by confusing proprietary estoppel with contract, or by failing to apply the remedial discretion. This is a high-yield, frequently tested area of SQE1.

What Is Proprietary Estoppel in SQE1?

Proprietary estoppel is an equitable principle that arises when: (1) the landowner makes an assurance (promise or representation) that the promisee will have an interest in or right over the land; (2) the promisee relies on that assurance; and (3) the promisee suffers detriment (loss) as a result of the reliance. If all three elements are satisfied, equity will intervene to prevent the landowner from going back on the promise. The remedy is discretionary and may be satisfied by granting a legal interest, compensation, or other equitable relief.

Proprietary estoppel is distinct from contract (which requires agreement, consideration, and formality) and from trusts (which require different elements). In the context of legal vs equitable interests, proprietary estoppel creates an equitable interest that may eventually be granted as a legal interest. Understanding proprietary estoppel is essential because it allows informal promises about land to have legal effect.

This topic connects closely to co-ownership and is a key part of the Land Law syllabus for SQE1.

Key Principles for SQE1

  • Assurance – The Promise or Representation: The landowner must make an assurance (promise or representation) to the promisee that they will have an interest in or right over the land. The assurance can be express (oral or written) or implied (from conduct). The assurance must be clear enough that the promisee could reasonably understand it to be a commitment. Vague or ambiguous statements may not be sufficient.

  • Reliance – Acting on the Promise: The promisee must rely on the assurance by acting on it. This might involve: moving into the property, improving the property, sacrificing opportunities elsewhere, contributing money to the property, or performing work or services. The reliance must be reasonable; the promisee must not have been aware of the true legal position or must have been misled.

  • Detriment – Suffering Loss: The promisee must suffer detriment (loss or disadvantage) as a result of the reliance. The detriment might be financial (money spent, opportunities lost) or non-financial (moving to the property, sacrificing career prospects, caring for the landowner). The detriment must be substantial and real; trivial or self-inflicted detriment may not suffice.

  • Thorner v Major – Key Case: The leading modern case, Thorner v Major, confirms that proprietary estoppel requires all three elements (assurance, reliance, detriment) and that the assurance must be about a specific interest (not a vague promise). The case also confirms that the detriment must be substantial and directly caused by the reliance, but that financial detriment is not always necessary (non-financial detriment can suffice).

  • The Remedial Discretion: Once proprietary estoppel is established, the court has discretion in granting the remedy. The court is not bound to grant the promised interest; instead, it can grant whatever remedy is necessary to do equity (prevent unconscionable conduct). The remedies available include: (1) granting the promised interest (legal title or equitable interest); (2) compensation (damages); (3) a lien over the property; or (4) other equitable relief.

  • Comparison to Contract and Trusts: Proprietary estoppel is distinct from contract (which requires agreement and consideration) and from trusts (which require different elements). An oral promise about land cannot be enforced as a contract (because s.2 Law of Property (Miscellaneous Provisions) Act 1989 requires writing), but it may be enforced through proprietary estoppel if the three elements are satisfied.

  • Informal Creation of Equitable Interests: Proprietary estoppel is a mechanism for creating equitable interests informally. Unlike a trust (which requires s.53 writing for land), an equitable interest can arise through proprietary estoppel without writing. This makes proprietary estoppel a powerful tool for protecting those who have relied on promises about land.

Exam tip

When faced with a proprietary estoppel question, systematically apply the three elements: (1) Is there a clear assurance by the landowner? (2) Did the promisee rely on it? (3) Did the promisee suffer detriment? If all three are satisfied, proprietary estoppel is likely established. Then ask: what remedy should the court grant? The court has discretion; it may grant the promised interest, compensation, or other equitable relief. The remedy should be proportionate to the detriment and the landowner's unconscionable conduct. Do not assume the promised interest is always granted; sometimes compensation or a lien is more appropriate.

How This Appears in SQE1 Questions

A scenario presents a farmer who has promised his son orally that he can live on the farm and work it after his death. The son moves into a cottage on the farm, works the farm without payment for 20 years, sacrifices job opportunities elsewhere, and improves the buildings. The farmer dies, leaving the farm by will to his daughter. The son claims he has a proprietary estoppel. The analysis requires: (1) assurance—the father's promise that the son will have the farm after his death (clear assurance); (2) reliance—the son moved to the farm, worked it, sacrificed opportunities, improved buildings (clear reliance); (3) detriment—the son sacrificed career prospects, worked without payment, spent time and effort (clear detriment). All three elements are satisfied. The court can order a transfer of the farm, a lease for life, or other equitable relief. The remedy should fit the detriment.

This is a classic SQE1 trap.

Common Mistakes Students Make

  • Treating proprietary estoppel as contract – Students sometimes try to enforce promises about land as contracts without recognizing that oral promises fail the s.2 writing requirement. Proprietary estoppel is the equitable alternative.
  • Overlooking the reliance element – Students often assume detriment alone is sufficient. All three elements must be present: assurance, reliance, and detriment.
  • Misidentifying the remedy – Students often assume the court will always grant the promised interest. The court has discretion and may grant compensation, a lien, or other remedies if more appropriate.
  • Confusing proprietary estoppel with trusts – Both create equitable interests, but the requirements are different. Proprietary estoppel requires assurance, reliance, and detriment; trusts require different elements (intention, certainty, constitution).

Quick Summary

  • Three elements: assurance, reliance, detriment – all must be satisfied for proprietary estoppel to arise.
  • Assurance is the landowner's promise or representation – express or implied from conduct.
  • Reliance is the promisee's action in response to the assurance – can be financial or non-financial.
  • Detriment is the loss or disadvantage suffered – must be substantial and directly caused by reliance.
  • The remedy is discretionary – the court can grant the promised interest, compensation, a lien, or other equitable relief to prevent unconscionable conduct.

Want to test this now? Try a few SQE1-style questions below before moving on.

Test Yourself

Test yourself

Quick check questions based on this article.

Question 1

Scenario

A grandmother owned a cottage in a rural village. She told her granddaughter on several occasions that the cottage would be hers one day. In reliance on this, the granddaughter moved into the cottage, gave up her rented flat, and spent £20,000 of her own money renovating the kitchen and bathroom. The granddaughter has lived in the cottage for six years, maintaining it and paying all outgoings including council tax and utility bills. The grandmother has now sold the cottage to a third-party purchaser without informing the granddaughter. The granddaughter was in occupation of the cottage at the time of the sale and the purchaser's solicitors did not inspect the property. The purchaser has been registered as the new proprietor and has asked the granddaughter to vacate. The cottage has a small workshop in the garden that the granddaughter uses for her pottery business. The cottage was sold for £195,000. The grandmother used the sale proceeds to fund her move to a retirement community. The purchaser obtained a standard mortgage from a building society to fund the purchase.

Does the granddaughter have a right that is enforceable against the purchaser?

Question 2

Scenario

A grandfather owned a large farmhouse with surrounding land. In 2008, he told his granddaughter that if she moved back from the city and helped run the farm, the farmhouse would be hers one day. The granddaughter gave up her job as a marketing consultant, moved into a cottage on the farm, and worked on the farm for no salary for 12 years. During this period, the granddaughter spent £40,000 of her own savings renovating the cottage. The grandfather was aware of these expenditures and did not object. He repeated the promise about the farmhouse on several family occasions, and the granddaughter's siblings were aware of the arrangement. The grandfather died in 2022 without having made a will. Under the intestacy rules, the farm passed to the grandfather's son, who is the granddaughter's uncle. The uncle now wishes to sell the entire farm, including the cottage. The granddaughter claims she has a right to the farmhouse based on her grandfather's promise. The uncle argues that the grandfather's promise was merely a statement of future intention and did not create any legal rights.

Which of the following best describes whether the granddaughter is likely to succeed in a claim based on proprietary estoppel?

Question 3

Scenario

A mother told her son that she would leave her registered freehold cottage to him in her will. Relying on this assurance, the son moved into the cottage and spent £30,000 renovating the bathroom and kitchen over a period of two years. The son gave up his rented flat to move into the cottage. The mother has now told the son that she has changed her mind and intends to sell the cottage to a third party. The son claims he has acquired a right to the cottage. The mother has recently obtained an estate agent's valuation of the cottage, though she has not yet listed it for sale. The son has no written agreement with the mother.

Which of the following best explains the basis of the son's claim to an interest in the cottage?

Practice with full exam-style questions

Try DemoView Pricing

Related Topics

Practise Proprietary Estoppel Questions for SQE1

Want to solidify your knowledge? ActusPrep provides realistic SQE1 questions tailored to this topic.

👉 Try our free demo: https://actusprep.com/demo 👉 View plans and pricing: https://actusprep.com/pricing